The present invention concerns a modular and adjustable staircase, prefabricated, designed to be installed in a rigid manner, and having at least one side which is equipped with a stiffener. Per stair and per side having a stiffener, a single element of the staircase, which is a cross piece with a heel, or a shim, must be adjusted or is predetermined in order to obtain the stair height desired. The shim is an element that is placed under the bottom side of the crosspiece to adjust the height of the step. The crosspiece with heel is a one piece element which likewise determines the height of the step.
Definitions of the terms used in the description and the claims:
floor to floor spacing: the space which separates the levels of a storey, that is, the vertical distance between the upper floor and the lower floor of the place where the present invention is to be installed.
rear of a stair: the part opposite the nosing.
tread: the horizontal spacing between two stair nosings, measured along the line of stride.
width of a stair: horizontal spacing which is perpendicular to the tread, measured between the stair extremities.
height of a stair: vertical distance between the level of the lower floor and the first stair, or between two consecutive stairs, or between the last stair and the level of the upper floor.
constant stair height: height obtained by dividing the floor to floor spacing by the number of stairs plus one.
The present invention, tending to bring improvements to patent #92 06170 published under #2691 489, differs from the prior techniques by its possibility for adjusting the heights of stairs and/or the tread and/or the width of each stair, which makes the staircase multi-purpose and suitable for installing in spaces with dissimilar volumes.
Thus the installation of the staircase can form only constant stair heights. Most of the known manufactured staircases require a staircase starting base which can be cut off at the top; which, compared to the vertical spacing of the other stairs shows a disparity in height which is detrimental to the climbing or descending cadence of the user. The base makes the structure uncomfortable and dangerous because of this disparity in height.
Patent DE-A-2619804 filed by the Carl Rehfeldt cement factory, describes several configurations for prefabricated staircases designed to be built using fiberglass-reinforced concrete. Contrary to the present invention, the various configurations described, as well as their manner of production, allow neither an adjustment of the geometry of a type of element of the prefabricated staircase, nor a choice of position and orientation of certain of the elements of the staircase in relation to one other in order to result in a possible in situ adjustment of the height and tread of the stairs, whereas the present invention allows all of that.